This invention relates to a support system which adjustably supports the support joists of a premanufactured building when permanently installed at a building site. More particularly, the invention includes a support system that can be adjusted in height so as to bear more or less of the weight of the premanufactured building.
Premanufactured buildings usually are constructed at a central location and transported to a permanent erection site. The typical premanufactured building structure includes a pair of parallel horizontal I-beam joists, with the building structure mounted on top of the joists. The joists typically are placed inwardly of the side edges of the building structure. When the building has been constructed, wheels are temporarily mounted to the joists so that the structure can be towed to the permanent erection site.
When the premanufactured building arrives at the erection site, the usual procedure for erecting the building is to prepare concrete support platforms in the ground, and to mount static piers on the platforms. The static piers are adjusted for proper height, and the building structure is then lowered onto the piers. Wedges, shims, or other fine adjustment devices can be urged between the piers and the joists so as to attempt to have all of the piers support approximately the same proportional load of the building structure.
The adjustment of the amount of support provided by each pier is a difficult task in that it usually is unknown as to how much weight each pier supports. For example, the ideal weight for a premanufactured building to apply to a pier might be 2000 lbs. However, visual observation of the building structure and the pier will not reveal the load applied by the building to each pier. If one pier supports a smaller load than the next adjacent pier, there is a likelihood that there will be some settling of the building structure downwardly on the pier that supports the larger load.
In the past, when a premanufactured building has experienced some settling after it has been mounted on piers, it is possible for the settling to be detected and remedied by placing wedges or shims between the piers and the joists where needed. However, even when the settling has been detected and remedied, it is not likely that the piers will each support approximately equal amounts of the load from the building structure, and additional settling of the building structure might occur.
It is to be foregoing problem that the invention disclosed herein is directed.
Briefly described, the present invention comprises an adjustable support system for a premanufactured building structure that includes adjustable piers that can be placed beneath the joists of the building structure. The adjustable piers can be adjusted vertically so as to assume more or less of the load of the joist and the weight of the building that is supported by the joist.
Typically, the premanufactured building structure will have been mounted on a plurality of static piers (as opposed to adjustable piers), with the static piers having been previously adjusted for height and therefore adjusted for bearing the load to be applied thereto by the building structure. Once the building has been mounted on the static piers, the adjustable piers are placed on the ground beneath the joists and between the static piers at the preferred locations along the lengths of the joists. The adjustable piers are adjusted upwardly as may be necessary so as to assume a predetermined load from the joists of the building structure.
Although the adjustable piers can be placed at any location along the lengths of the joists, the preferred locations are at the ends of the joists, and therefore at the ends of the building structure, and at an intermediate position along the lengths of the joists and the intermediate portion of the building structure. The placement of the adjustable piers at the ends of the joists provides an ideal support arrangement at a critical part of the building structure. For example, if support provided by a static pier at the end of the structure is insufficient, the end of the building structure may settle, sag or sway. However, if an adjustable pier is provided at this location, the installer or the occupant of the building structure can adjust the load supported by the adjustable pier, thereby eliminating the settlement, sag, sway, or other symptom of insufficient support.
More particularly, the adjustable piers each include a support platform, preferably formed of sheet metal, that includes cleats at its edges that engage the ground on which the support platform is placed so that the support platform is not movable horizontally. Typically, a pair of struts are oriented at sloped angles extending between the support platform and the joist to be supported. A joist connector connects the upper or joist end of each strut to the joist, and the lower or platform end of each strut is mounted to the support platform. One of the ends of the strut, usually the platform end, is movably supported so that the angle of the slope of the strut can be changed, thereby changing the vertical height of the strut.
In a preferred embodiment of the invention, the lower or platform end of each strut is received in a clevis that is rigidly mounted to the support platform, and a travel screw is mounted in the clevis, with the lower or platform end of the strut being mounted to the travel screw. An adjustment nut is mounted to the travel screw in engagement with the lower end of the strut. Upon rotating the nut on the travel screw, the lower end of the strut moves horizontally with respect to the support platform while the upper end of the strut, being connected to the joist of the building does not move horizontally but simply rotates about its connection to the joist. This tends to adjust the angle of the slope of the strut. This effectively causes the upper end of the strut to increase or decrease its vertical displacement with respect to the lower end of the strut, thereby increasing or decreasing the load from the joist borne by the strut.
Usually a pair of struts will be used in each adjustable pier. Preferably, the struts of each pair of struts are sloped in opposed directions so that the horizontal forces applied through the struts cancel each other. For example, the pair of struts can be formed in an xe2x80x9cXxe2x80x9d configuration, in a xe2x80x9cVxe2x80x9d configuration, or in an inverted xe2x80x9cVxe2x80x9d configuration.
Typically, a torque wrench will be used to rotate the nut on the travel screw, so as to determine the load borne by the strut. For example, the application of a predetermined torque to the nut results in the strut bearing a predetermined vertical load at a prescribed angle of the strut.
Also, indicia is applied to the sidewalls of the clevis that receives the lower end of each strut to indicate the angle at which the strut extends upwardly from the support platform toward the support joist of the building structure. For example, the installer will be instructed to attempt to achieve an angle of between 40-50xc2x0 between the strut and horizontal, with the preferred angle being 45xc2x0. This range of angles typically provides adequate vertical support for the building structure and also applies resistance to longitudinal movement of the joist in response to wind loads or seismic movement applied to the building structure.
Thus, it is an object of this invention to provide an infinitely adjustable support system for a premanufactured building structure that is expedient to install and which can be adjusted to support a prescribed load of the building structure.
Another object of this invention is to provide an improved adjustable pier which functions as an adjustable support system for a premanufactured building structure, with the support system having the ability to balance the load applied by the building structure to a multiple number of adjustable and static piers.
Other objects, features, and advantages of the present invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings.